Traversing measurement system for a dryer and associated method

ABSTRACT

A system and method for obtaining measurements across a width of material being processed is provided, which includes a near-infrared (NIR) detector head ( 102 ) which reads and transmits an NIR signal that has been reflected from the material, and a fiber-optic cable ( 106 ) through which the signal is transmitted to a processor located remotely from the material being processed. A moisture level reading can be obtained in a drying apparatus and used to aid in controlling the operation of the dryer. The detector head ( 102 ) is mounted to a traversing beam (105) and the detector head ( 102 ) is capable of traveling to positions across the width of the material being processed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is directed to a system and method for obtainingmeasurements across the width of a material being dried in an industrialdryer.

2. Description of Related Art

Industrial dryers are used, for example, in drying tobacco in variousprocessed forms prior to the tobacco being used in producing finishedproducts. Other products also require drying as part of the processingto produce the final product. In certain tobacco drying processes, forexample, an “apron”, or substantially continuous moving sheet, oftobacco in semi-processed condition is passed through dryer units at oneor more stages prior to packaging for shipment to a tobacco productsmanufacturer. The tobacco is checked for moisture content after it hasbeen processed through the dryer, in order to determine whether themoisture level of the tobacco is at or below the maximum moisture levelas dictated by the tobacco products manufacturer. If the moisture levelexceeds the maximum level imposed, the tobacco must be reprocessed atgreat expense to the supplier, in order to be sold to the tobaccoproducts manufacturer.

Similar scenarios are present in a variety of industries outside thearea of tobacco production, in which the moisture content or otherproperties of the intermediary product must meet specifications dictatedby the purchaser of the intermediary product. In such instances wheremoisture content is measured only at the completion of processing, thesame situation can arise that the intermediary product must be furtherprocessed in order to be accepted by the purchaser.

Moisture control in apron style tobacco dryers has long been a challengeto the industry. This is due to the fact different tobaccos and tobaccoblends have varying densities, as well as percentages of casing,affecting the tobacco carpet depth and/or mass flow throughput. The leafstalk position and the environmental conditions at the time ofprocessing also contribute to changes in the drying process. Thesechanges represent more or less work/energy transfer required to achievethe desired results. This causes the operator to adjust both heating(drying) and re-ordering (moisturizing) zones of this multiple stageprocess. Most tobacco processing lines have dryers with three or morezones of heating, one or more zones of cooling, and two or more zones ofre-ordering.

Processing originally depended entirely on the acquired skill of theoperator's hand to determine the approximate moisture content of thetobacco discharging from the dryer. With the reduction of cost for astandard on-line moisture gauge to less than $10 K per unit, many dryersare now fitted with moisture gauges at the discharge to assist operatorsin monitoring the quality of the product exiting the dryer. To date,most operations have relied on this final moisture value supported bylab results, in conjunction with measured internal dryer temperatures,to make necessary adjustments to control the process.

Recently, with the need to achieve the highest production rates possiblewith existing equipment and ever tightening customer product qualitycontrol standards, tobacco processors have been looking for a method tobetter control the drying process and reduce standard deviation. Onemajor problem has been that the drying process is both multiple zone andbi-directional. Therefore, no reliable means for determining the averagemoisture after drying and before re-ordering was readily available. Someprocessors have placed standard on-line moisture gauges inside thecooling sections of dryers with limited success. Mainly because it is asingle point-measuring device mounted at a fixed position along thelongitudinal axis of an apron style dryer, the data does not provide atrue profile of the product across the entire dryer width and thereforeis of limited use. This is further complicated by the fact standardphotometers (moisture gauges) in this environment are operating near orat their maximum operating temperature, affecting both their performanceand life cycle (MTBF).

It is therefore a principal object of the present invention to provide asystem and method for taking measurements of, for example, moisturelevels present in a moving product stream, and employing thatinformation to aid in determining whether the product will meet moisturelevel requirements imposed by a purchaser of the product.

It is a further principal object of the present invention to provide asystem and method for taking measurements of, for example, moisturelevels present in a moving product stream, and employing thatinformation in a control loop or control scheme for controlling processequipment used to produce the desired product.

It is a further principal object to provide a system for measuringparticular properties of a material being processed in an enclosed area,which deploys a compact detector head within the enclosed area, andwhich delivers an NIR reflected energy to an electronics packageexternal to the enclosed area for processing.

SUMMARY OF THE INVENTION

The above and other objects of the present invention are achieved byproviding a fiber-optic based property measurement system which isoperable to detect near-infrared (NIR) energy in a product travelingpast a fiber-optic detector head, and in which the NIR energy detectedcan be correlated to a property or properties of the traveling product.The measurement system employs a bracket or “traverse beam”, acrosswhich the fiber optic head is driven, so as to permit measurements to betaken at various positions across the width of a product stream.

The fiber optic based measurement system provides a non-contactdetection system which thus performs the measurements non-destructively.The system, which is made up of the fiber optic head, the traverse beam,the means for driving the fiber-optic head across the traverse, and theother associated parts and components, provides a very compact detectorunit, which is thus capable of being installed within various types ofprocessing equipment, thereby permitting in situ measurements to betaken and used in any manner desired, for example, as feedbackinformation to an equipment controller.

It was determined that, if a reliable measurement could be made in thecooling section, the operator could control the heating zones to preventoverdrying the tobacco. Since the smoking flavor and degradation of theproduct are both linked to the drying process, this is viewed as animportant step towards improving process control and product quality.The measurement system developed as an aspect of this invention uses aNIR fiber optic cable and remote probe mounted on a linear traverse toallow the NIR electronics to be located outside of the dryer and alsoallow the measurement of the surface moisture across the entire apronwidth, providing a true average surface moisture value as well asdefining the drying profile. The profiles provided can be used to adjustproduct in-feed sweep speed and/or energy distribution to reduce anyunnecessary induced moisture deviation from the average value.

The system measures process variables/constituents on a continuous basisand collects data at specified (customer or otherwise) positions acrossthe entire apron width. To improve repeatability, single measurementelectronics is provided for each process variable (PV). The data isdisplayed in actual engineering units through a color touch screendisplay mounted in the control cabinet provided or optionally mounted upto 150′ away from the control cabinet. The system is designed toautomatically trend collected data with reference to real time anddevelops dryer profile bar charts that are updated regularly. From thevisual graphics provided, the dryer performance can be quickly reviewedso corrective action can be made. This allows improvement of the dryer'sfinal product output consistency; thereby reducing standard deviation ofthe final product. In addition, the system provides real timemeasurements of process variables for use in both feedback and feedforward control loops providing optimum dryer performance and maximumreturn on investment.

The system design can preferably include measurements such as tobaccocarpet surface moisture, product temperature, bed depth and coolingsection ambient air temperature measurements, as well as the ability tomeasure inner core moisture and temperature. Relative humiditymeasurements can also be provided if desired. Operator input fields areprovided on an input screen for entry of product identification andtarget moisture value. From the trending/chart menu selection on theinterface, the real time and historical data can be reviewed in the formof trend lines and bar charts. Due to a finite electronic data storagecapacity of the system, new data will, at some point, overwrite theoldest data on the flash memory card. The system also allows for thecontinuous archiving of data to a CSV file located on a PC via 10/100Ethernet network.

The system includes the ability of the sensor to return to a homeposition, which is preferably in an enclosure positioned flanking theside wall of the process equipment, thus providing access to the sensorcarrier for periodic maintenance and validation. The enclosure ismounted to the vertical dryer frame member on the door closure (latch)side. The traverse assembly requires an approximate 20″ square doorcutout and a 24″ high clearance above the apron. This measurement systemwould also traverse the entire width to provide average and profile datafor both product moisture and temperature.

The electronics package that traditionally has been provided in the samehousing as the NIR optical detector components is, in the presentsystem, disposed at the exterior of the processing equipment, and theNIR optical detector components and associated processing electronicsare optically coupled by a flexible fiber-optic cable which extends fromthe NIR optical detector inside the processing equipment to anelectronics package mounted at the exterior of the equipment. Thisallows the use of a much more compact detector head inside theprocessing equipment.

The system of the invention further optionally includes a blower oragitator which can be intermittently used to temporarily or permanentlyremove an outer surface or layer of the product being processed, so thatthe properties of the product material below the outer surface may bedetected by the fiber optic head. Thus, for example, in a product dryer,in which an exposed surface of the product may be dried to a greaterdegree than the underlying material, a more accurate measurement of theoverall moisture level in the product may be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will be morereadily understood from a reading of the ensuring detailed descriptionof the preferred embodiment of the invention, taken in conjunction withthe accompanying drawings, in which:

FIG. 1 is a substantially schematic side view of a preferred embodimentof the present invention as installed in an apron dryer employed to drytobacco intermediary products.

FIG. 2 is a substantially schematic top view of the apron dryer of FIG.1, showing the measurement system according to a preferred embodiment ofthe present invention installed therein.

FIG. 3 is a front elevation view of the general arrangement of thesystem mounted in a tobacco dryer.

FIG. 4 is a side elevation view of the general arrangement of thesystem, as viewed from the exterior of the tobacco dryer.

FIG. 5 is a perspective view of the carrier bracket and componentsmounted thereto, in accordance with a preferred embodiment of thepresent invention.

FIG. 6 is a perspective view of the traverse beam and associatedcomponents in accordance with a preferred embodiment of the presentinvention.

FIG. 7 is a substantially schematic cutaway view of the detector head inaccordance with a preferred embodiment of the present invention.

FIG. 8 is an enlarged view of the fiber optic cable carrier illustratedin FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIGS. 1 and 2, a measurement system 100 is shownin schematic form as installed internally in what is referred to in thetobacco processing industry as an apron dryer 10. It is to be noted thatthe discussion of the invention as used in connection with an aprondryer, and in connection with the drying of tobacco, is solely forillustrative purposes, as the measurement system can readily beincorporated into any number of types of processing equipment, and issuitable for use in any applications in which a product properly orproperties can be correlated to the emanation/reflection from theproduct of near-infrared (NIR) energy.

As other examples in the processing of tobacco, near-infrared energyreflected from the surface of the tobacco product can be used todetermine the nicotine content of the tobacco, the sugar content, and/orthe fat content, as well as other properties. A signature reflectedenergy pattern can readily be developed for each of these properties, aswell as for other properties. When any or all of these other propertiesare determined to be of interest, the apparatus and method can readilybe equipped or programmed, in a manner that will be readily apparent tothose of ordinary skill in the art, to interpret the NIR energy detectedsuch that the desired information can be provided. In addition, thesystem and method can be used in the processing operations for otherproducts.

The apron dryer 10 in FIGS. 1 and 2 is commonly used to dry a partiallyprocessed tobacco product known in the art as “thrashed tobacco”, ortobacco leaves that have been destemmed. The specific details of theconstruction of the apron dryer, and its specific modes of operation,are well understood in the dryer art, and do not form a specific part ofthis invention. As relevant to the present invention, it is noted thatthe apron dryer 10 has three basic sections, a heating section 12, madeup of three heating units H1, H2, H3, a cooling section 14, made up ofthree cooling units C1, C2, C3; and an “ordering” section 16, made up ofthree ordering units, O1, O2, O3.

In the heating section 12, heated air is blown across the apron 18 oftobacco, to drive off moisture. The apron 18 is a substantiallycontinuously moving sheet made up of tobacco leaves, and generally willhave a thickness T on the order of 2-4 inches, and a width W on theorder of twelve (12) feet. Aprons may actually be processed in discretelengths, such as on the order of 100 feet in length, but may be regardedas being of substantially indeterminate and continuous length for thepurposes of this invention.

The heated air is blown through the thickness of the apron in opposingdirections, as indicated by the arrows in FIG. 1, in order to attempt toachieve even drying through the thickness of the apron. The apron 18travels on a belt 20, normally made of highly perforated metal, suchthat the heated air can travel through the apron 18 in both directionsindicated.

The apron passes from the heating section 12 to cooling section 14,where unheated or chilled air is blown through the apron to cool thematerial to substantially ambient temperature, or some other desiredtemperature. From the cooling section, the apron passes into an orderingsection, in which the tobacco in the apron has moisture added via theintroduction of steam or water through nozzles disposed in these unitsO1, O2, and O3.

The reason that the thrashed tobacco is first dried and thenremoisturized is that a certain moisture level in the dried product isdesired, yet the moisture content prior to drying is unevenlydistributed in the thrashed tobacco, in which excessive moisture may beretained in any remaining stems or in the thicker portions of thetobacco leaf. Excess concentrated moisture of this type leads to productstorage problems, in that mildew and rot can develop in the product insuch situations. Thus, the product is generally dried beyond the levelnecessary to remove concentrated moisture, and is remoisturized in amore evenly distributed reordering process step.

In the operation of apron dryers in the prior art, the moisture of theproduct exiting from the dryer is not measured as the process is takingplace, but is later measured to determine if the product meets themoisture content standards of the customer for whom the semi-finishedtobacco product is to be supplied. Product which does not meet themoisture content requirement must undergo further processing in order tobe accepted by the customer.

The system and method of the present invention minimize the chances thatproduct exiting the apron dryer will exceed maximum moisture levelsimposed by customers, while, at the same time, allow the producer toprocess tobacco to have moisture levels close to such imposed maximums.This can increase the profitability of the process, in that tobacco inthe semi-finished form is sold on a per pound basis, and, when themoisture content is at or near the imposed maximum, there is less actualtobacco leaf in each pound of the delivered product.

The system of the present invention achieves the objectives byperforming an in situ measurement, in this case a moisture measurement,thereby enabling the apron dryer 10 to be controlled in a real time ornear real time manner, such that the moisture content of the tobaccoexiting the drier is as close as possible to a desired level. Thedesired level would generally be set with the intent of having thedelivered product come close to, but not to exceed, the maximum imposedby the customer, and, at the same time, minimizing the chances ofrejects due to excessive moisture content. The system also providesthese measurements across the width of the tobacco apron, whichinformation can be used to ensure consistency across the entire apron.

The measurement system 100 includes a fiber optic NIR detector head 102,which is capable of emitting NIR energy toward the surface of thetobacco apron 18, and receiving back a reflected NIR energy. Thedetector head 102 will be referred to herein as a “passive” opticalhead, in that the detector head will not process the reflected energysignal itself, but will merely serve as the front end of a conduit to anelectronics package 300 located external to the dryer 10, where thedetected NIR energy is to be processed. The detector head 102 is mountedon a bracket 104, and the bracket 104 is movingly mounted to a traversebeam 105. The traverse beam 105 is installed in the dryer to spanessentially the entire width of the product, here, the apron of tobacco18, which travels through the dryer. The fiber optic detector head 102is coupled to a fiber optic cable 106 that is operable to transmit thedetected NIR energy to a processor.

Fiber optic cable 106 may preferably comprise a bundle of opticalfibers, for example, about 200 to 300 fibers, that are secured togetherto form a single “cable” having a combined diameter preferably in therange of about ⅛-¼ inch. Such a cable will be sufficiently flexible orpliant to be able to withstand the bending or deformation that the cable106 will undergo as the detector head 102 traverses the width of thetobacco apron 18. The cable 106 is coupled to the detector head 102 in amanner such that the detected NIR energy will pass from the head/or intocable 106.

FIG. 7. shows, in substantially schematic form, a cutaway view of thedetector head 102. It can be seen in this view that the detector head102 houses a pair of mirrors 160, 162 and contains a lens 164 at a lowersurface thereof. Fiber optic cable 106 is secured to an upper end of thedetector head, and the bundle of optical fibers forming the fiber opticcable are oriented such that they are capable of delivering NIR energyessentially vertically downwardly into the interior of detector head 102(see solid line representing NIR energy path). A first mirror 160 has anon-linear or non-planar mirrored surface which, as it is reflecting theNIR energy transmitted by the fiber optic cable 106, also conditions orfocuses the incoming energy as desired. The energy is reflected atsubstantially 90°, to a horizontal path. A second mirror 162, reflectsthe energy again downwardly through a lens 164 disposed at the lowersurface of the detector head 102.

The second mirror does not further condition the energy beam, but ratheronly reflects that energy. Similarly, the lens 164 is preferablyneutral, meaning that it does not alter the energy beam in anysignificant way. The lens is provided principally to protect theinterior of the detector head from the environment outside the detectorhead.

The NTR energy is thus directed downwardly toward the surface ofinterest, which, in the case of a tobacco dryer, is the traveling apron18 of tobacco. The NIR energy is reflected off of the surface, with someabsorption or diffraction occurring as a result of the condition andproperties of the surface of interest. The reflected potion of theenergy (see broken line path in FIG. 7) is received back through lens164, and is directed back to fiber optic cable 106 by mirrors 162 and160. The fiber optic cable 106 then channels the reflected energy to theprogrammable logic controller and attendant electronics 300 foranalysis. A material property of interest, for example, moisture, may bedetermined based upon the characteristics of the reflected energy. Othermaterial properties, such as sugar or nicotine content, or the like, mayalso be characterized in terms of reflected NIR energy, and thecontroller can be programmed to determine those other properties of thematerial/product under analysis, as well.

The construction of traversing bracket or beam 105 is generally known inthe art, and may be used in connection with the present invention. Asupport tube 107, which may preferably be an aluminum tube of square orrectangular cross section, is preferably mounted by end supports 109 ateither end of the tube 107. The end supports 109 may preferably besimple brackets having a box-shaped “U” which receives an end of thesupport tube therein. These end supports 109 are secured to the innerside walls of the process equipment, here, a tobacco dryer. Anespecially advantageous aspect of the detector head 102/traverse 105combination employed in this invention is that it provides a verycompact design which can be fitted into clearance spaces of as small as24″ from the top surface of the traveling product stream. The principalrequirements of the traversing beam 105 are that the beam besufficiently strong to support the detector head and attendant equipmentabove the product passing through below, including means for driving thedetector head 102 and bracket 104 across the beam.

As the product travels past and underneath the detector head 102,detector head emits an NIR signal, and receives back a reflected NIRsignal from the product. This information is then preferably transmittedthrough fiber optic cable 106, to a processor (discussed later) that iscapable of correlating the reflected signal to a moisture content of agiven product. Preferably, an IR sensor 130 is also provided, of a typethat is commercially available, to measure temperature, as well.

Because dryers can dry a product unevenly across the width of the apron,the system of the present invention, which mounts the detector head 102on a bracket 104, which in turn is mounted on traverse beam 105, isespecially well-suited to obtain moisture measurements at variouslocations across the width of the apron. The traverse beam 105 ismounted transversely to the direction of product travel or flow. Thetraverse beam 105 is preferably equipped with means operable to movebracket 104 and detector head 102 across the beam. One preferred movingor driving means is a hydraulically operated linear actuator 200 mountedatop the beam 105. One such preferred linear actuator is the PrecisionAire PSA-15, available from Tol-o-matic, Inc., of Hamel, Minn.

The detector head control system 300 is preferably set up to control thelinear actuator to stop the detector head at specific spaced-apartintervals across the width of the apron 18. The detector head will thusbe able to take moisture and temperature measurements at desired pointsacross the entire width, and will be able to detect any patterns ofuneven drying from side-to-side on the apron of material. This data canbe used to adjust the air blowers or the temperature of the air used inthe heater section, or, possibly, such information might lead to theconclusion that the heating unit used to heat the air is malfunctioningand requires maintenance.

Another preferred, but optional, feature of the present invention is theprovision of a pneumatic nozzle or nozzle array 110, which can be usedto agitate or temporarily or permanently displace or remove a top layerof the product traveling past the detector head 102. In the case ofusing the system in an apron dryer, the nozzle 110 is carried by thebracket 104, which secures the detector head to the traverse such thatthe nozzle 110 is positioned at a fixed position relative to thedetector head, at an upstream position therefrom. It is to be noted inFIG. 2, that the nozzle array 110 is shown connected to the broken lineversion of detector head 102, and the solid line version of detectorhead 102 is shown in a different position, for purposes of clarity ofillustration.

The nozzle or nozzle array 110 is preferably oriented to blow air in adirection transverse to the direction of product flow or travel. Inaddition, the nozzle or nozzle array is preferably oriented at about a45° angle from horizontal, or from the upper plane of the apron orcarpet 18 of tobacco traveling past. Air blown through nozzle(s) 110will, in the case of processing thrashed tobacco, temporarily lift oneor more leaves from the surface of the apron, and may actually flip theone or several leaves off of the surface, in either case exposingproduct below the surface which may have a different moisture contentthan the product initially at the surface. Because the nozzle 110 islocated immediately upstream of the detector head 102, the fiber opticNIR detector will be able to determine the moisture content, and the IRsensor, the temperature, of the product of a subsurface level. This isexpected to further aid in characterizing the overall moisture contentof the apron or carpet of tobacco, which, as noted previously, may befrom about 2-4 inches in thickness. In turn, such information isexpected to enable improved process control such that the final productwill have the desired moisture properties, e.g., moisture content. Thenozzle 110 will be connected to an external source of plant air orindustrial air, by a hose 122 extending from the nozzle 110 to theexterior of the dryer or other equipment in which the system isinstalled.

The movement of fiber optic cable 106 is carefully controlled by cableguide 130. Cable guide 130 comprises a series of pivotable metal links,of, for example stainless steel or aluminum, with the adjacent linksbeing connected to each other. The fiber optic cable is carried in theinterior of this guide, between pins that span the spacing betweenopposing links. The cable guide is secured to bracket 104 adjacent theposition at which fiber optic cable 106 is coupled to detector head 102,and is of a length approximately equal to the span of beam 105. Thecable guide will pivot or fold back on itself as the bracket 104 travelsfrom one end of the beam 105 toward the other end of the beam. The cableguide preferably maintains a predetermined radius of bending, such asabout 6-9 inches, in order to prevent the optical fibers from being benttoo severely, which could lead to breakage of the optical fibers.

The system will also preferably include a human/machine interface 112that may include a screen display indicating date, time, traverseposition, average moisture, average product temperature, measurementstatus, and manually entered product identification information, such asan identification number and a target moisture set point value. Thesystem may optionally measure or monitor product parameters such asproduct (apron or carpet) height and ambient temperature.

The human/machine interface may include a graphing menu option, which,when selected, can present historical information such as:

-   -   a continuous graph of the average moisture/temperature or other        constituents across the dryer width as a function of time, for        the normal product surface, and/or the inner core surface;    -   a continuous graph showing values of the moisture deviation of        the detected average moisture as compared against the target        moisture set point value or other constituents across the dryer        width as a function of time, for the normal product surface        and/or the inner core surface;    -   a continuous graph of the moisture/temperature trend at any of        the preset measurement locations across the dryer width as a        function of time; and/or    -   a bar chart of two-color bar graphs indicating, for each of the        preset measurement locations across the width of the dryer,        averaged moisture and temperature lines for the entire width for        a selected time period during which continuous measurements were        being made, showing the percentage deviation of moisture and        temperature from the average shown on each bar graph.

The system further will preferably employ a programmable logiccontroller 300 that, in combination with the human/machine interface,will control the operation, calibration, data acquisition and analyticalmathematical calculations for data archiving, for graphics, and toprovide real time data, as the foundation for statistical processcontrol. This set of electronics will preferably be mounted to anoutside wall of the piece of process equipment, or be positioned at someremote location.

The controller will include standard components, known in the art of NIRsensors, that are capable of generating an NIR energy signal to betransmitted to and through fiber optic cable 106, and are capable ofreceiving and interpreting the NIR signal that is reflected back fromthe product being inspected, and channeled through the fiber opticcable. Once the NIR signal is interpreted, that information can be sentto a feedback or feed-forward controller 302, of a type known generallyin the art, to be used in controlling the operation of the processequipment.

The provision of a human/machine interface 304 which can generate trendlines and profile (across the width of the apron) bar charts provides asignificant tool for understanding the process taking place, by showingthe inconsistencies in the process. The trend line information may becontinuously updated, and the bar charts may preferably be updated onthe order of every few minutes to show measured process variabledeviation in the product in both the product feeds along thelongitudinal axis of the dryer, as well as the drying process-inducedgradient across the width of the dryer. Such data allows operationalpersonnel to make adjustments in the operation of the dryer and todocument the results of the adjustments immediately, thereby improvingconsistency and reducing standard deviation.

The process variable measurements may also preferably be used, as notedabove, in either or both feedback or feed-forward control loops 302 toachieve optimum dryer performance.

While the illustrated embodiments provide an indication as to thepreferred embodiment for carrying out this invention, it is to beunderstood that the true scope of this invention is set forth in theappended claims, and that variations from the preferred embodiments willfall within the scope of the appended claims.

1. A method for measuring a moisture level of a moving apron of tobaccoin a tobacco dryer, comprising: (a) projecting a near-infrared (NIR)signal onto the moving apron of tobacco at a plurality of locationsacross a width of the moving apron by moving an NIR detector head toeach of said plurality of locations; (b) receiving, in said NIR detectorhead, a reflected NIR signal, at each of said plurality of locations;(c) transmitting said reflected NIR signal through a fiber-optic cable,to a signal processing electronics package disposed exteriorly of thetobacco dryer; and (d) processing said signal in said electronicspackage to determine a moisture level at each of said plurality oflocations.
 2. A method as set forth in claim 1, further comprisingdisplaying information in visible form which is representative of themoisture level determined at each of said plurality of locations.
 3. Amethod as set forth in claim 1, further comprising employing saidmoisture level determination at said plurality of locations in a processcontrol loop to control said tobacco dryer.
 4. A method as set forth inclaim 3, further comprising repeating steps (a)(d) periodically, andemploying said periodically obtained moisture level determinations insaid process control loop.
 5. A method for measuring at least onephysical property of a moving product being processed, said productbeing of indeterminate length, the process comprising: (a) projecting anear-infrared (NIR) signal onto the moving product at a plurality oflocations across a width of the moving product by moving an NIR detectorhead to each of said plurality of locations; (b) receiving, in said NIRdetector head, a reflected NIR signal, at each of said plurality oflocations; (c) transmitting said reflected NIR signal through afiber-optic cable, to a signal processing electronics package disposedexteriorly of the tobacco dryer; and (d) processing said signal in saidelectronics package to determine said at least one physical property ateach of said plurality of locations.
 6. A method as set forth in claim5, further comprising displaying information in visible form which isrepresentative of the at least one physical property determined at eachof said plurality of locations.
 7. A method as set forth in claim 5,further comprising employing said physical property determination atsaid plurality of locations in a process control loop to control saidmethod.
 8. A method as set forth in claim 7, further comprisingrepeating steps (a)-(d) periodically, and employing said periodicallyobtained physical property determinations in said process control loop.9. Apparatus for obtaining measurements of at least one property in asubstantially continuously traveling product stream comprising: adetector head for transmitting and receiving a near-infrared (NIR)signal generated by a remote electronics package, said detector headbeing mounted on a bracket; a traversing beam extending transverselyacross an entire width of said continuously traveling product stream,said traversing beam having said bracket mounted thereon, said bracketbeing movably mounted to said traversing beam; means for transportingthe bracket across a width of said traversing beam, said transportingmeans being capable of stopping said bracket at a substantiallycontinuous range of positions across said width; a fiber optic cableoperatively coupled to said detector head and extending to a positionphysically remote from said traversing beam and said detector head; anelectronics package coupled to said fiber-optic cable at said physicallyremote position, said electronics package including means for generatingan NIR signal and for emitting said NIR signal to and through saidfiber-optic cable, said electronics package further including means forreceiving reflected NIR signals from said fiber-optic cable, and meansfor processing said reflected NIR signals to determine at least oneproperty of said product stream corresponding to said reflected NIRsignal detected at a particular position on said traveling productstream.
 10. A method for measuring a moisture level of a moving apron oftobacco in a tobacco dryer, comprising:
 9. Apparatus for obtainingmeasurements of at least one property in a substantially continuouslytraveling product stream comprising: a detector head for transmittingand receiving a near-infrared (NIR) signal generated by a remoteelectronics package, said detector head being mounted on a bracket; atraversing beam extending transversely across an entire width of saidcontinuously traveling product stream, said traversing beam having saidbracket mounted thereon, said bracket being movably mounted to saidtraversing beam; means for transporting the bracket across a width ofsaid traversing beam, said transporting means being capable of stoppingsaid bracket at a substantially continuous range of positions acrosssaid width; a fiber optic cable operatively coupled to said detectorhead and extending to a position physically remote from said traversingbeam and said detector head; an electronics package coupled to saidfiber-optic cable at said physically remote position, said electronicspackage including means for generating an NIR signal and for emittingsaid NIR signal to and through said fiber-optic cable, said electronicspackage further including means for receiving reflected NIR signals fromsaid fiber-optic cable, and means for processing said reflected NIRsignals to determine at least one property of said product streamcorresponding to said reflected NIR signal detected at a particularposition on said traveling product stream. (a) projecting anear-infrared (NIR) signal onto the moving apron of tobacco at aplurality of locations across a width of the moving apron by moving anNIR detector head to each of said plurality of locations; (b) receiving,in said NIR detector head, a reflected NIR signal, at each of saidplurality of locations; (c) transmitting said reflected NIR signal to asignal processing electronics package; (d) processing said signal insaid electronics package to determine a moisture level at each of saidplurality of locations, and (e) employing said moisture leveldeterminations at said plurality of locations in a process control loopto control said tobacco dryer.
 11. A method as set forth in claim 10,further comprising repeating steps (a)-(d) periodically, and employingsaid periodically obtained moisture level determinations in said processcontrol loop.
 12. Apparatus for obtaining moisture measurements in asubstantially continuously traveling tobacco product stream in a tobaccodryer comprising: a detector head for transmitting and receiving anear-infrared (NIR) signal, said detector head being mounted on abracket; a traversing beam extending transversely across an entire widthof said continuously traveling tobacco product stream, in said tobaccodryer, said traversing beam having said bracket mounted thereon, saidbracket being movably mounted to said traversing beam;